MEXICO CITY.- Besides the loss of human lives, earthquakes and other disasters can damage built heritage of a country, symbol of identity for its inhabitants. A successful case of heritage recovery is described in the book Los monumentos arqueologicos de Monte Alban ante los desastres naturales: el sismo de 1999. (Archaeological Monuments in Monte Alban Facing Natural Disasters: The 1999 Earthquake).

Published by the National Institute of Anthropology and History (INAH), the book details the way structural problematic of Zapoteca constructions was approached, after the 7.4° (in the Richter scale) earthquake that shook Oaxaca state in September 30th 1999.

The experience of the project financed by Fondo de Desastres Naturales, FONDEN (Natural Disasters Fund) is narrated in the publication. An interdisciplinary team was integrated, which established regulations to give the best treatment to affected monuments. Today, buildings are closely monitored with special equipment donated by Japanese Government.

Dr. Nelly Robles Garcia, director of Monte Alban Archaeological Zone, recalled that more than 20 Prehispanic constructions presented serious damage. Worker teams were integrated by 200 persons, and the technical group was formed by 50 professionals, among them archaeologists, architects, engineers, photographers and drawers.

This unprecedented effort made the recovery of the buildings possible within a year, mentioned the coordinator of Los monumentos arqueologicos de Monte Alban.

Among most relevant issues part of the Scientific Collection book is the one related to prevention; there is a wrong idea about Prehispanic monumental structures being unharmed after a natural disaster, commented the archaeologist.

Experience with affected structures of Monte Alban, Mitla and Lambityteco is that they are vulnerable. Damage presented was not only as consequence of the 1999 tremor, but prior quakes; it was really a series of damages.

Some structures collapsed; complete walls came down, and some monuments were sectioned, as the ground, literally, gaped open. Those were the most dramatic cases.

Several buildings presented cracks and some columns dislodged from their bases; other structures suffered displacements. Work included restitution of structural stability of monuments as well as detailed conservation and restoration tasks, explained Nelly Robles.

The edition explains methodology applied in different work fronts that may be employed in other archaeological zones in the event of a disaster, attended according the needs of damaged buildings.

As part of Monte Alban Archaeological Zone Management Plan, monuments are subject of permanent monitoring, having each of them a medical history. Robles, also president of the INAH Council of Archaeology, explained screening can be divided in 3 kinds.

We count on with a seismometer or accelerometer donated by Japanese Government. 20 buildings damaged are constantly being monitored, and staff from UNAM (Universidad Nacional Autonoma de Mexico) Institute of Geophysics collaborate interpreting data.

Temperature and humidity variations are measured with a thermohygrograph, with the objective of following up preservation state of mural painting at Monte Alban.

Direct supervision is the third work front. Experts check up, every 2 months, fissures at structures, spreading a plaster seal to control them; if they break, they are pointing out there is movement at the building. A wider plan to stabilize construction is programmed.

This is how, after 10 years of opportune attention, INAH has acknowledged consolidation of diverse structures of Monte Alban damaged by the 1999 quake, and they no longer represent a threaten for visitors.

This Oaxaca archaeological site was inscribed in the United Nations Educational, Scientific and Cultural Organization (UNESCO) World Heritage List in December 1987. It was the capital city of Zapoteca people and developed between 500 BC and 800 AD, reaching an occupation of 35,000 inhabitants.